Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: period of glyphosate treatment on oak seedlings: phenological and physiotogical aspects. | 824s Ann. Sci. For. 1989 46 suppl. 824s-827s Forest Tree Physiology E. Dreyer etal. eds. Elsevier INRA Effects of the period of glyphosate treatment on oak seedlings phenological and physiological aspects c. Fabert1 2 H. Frochot1 and p. Dizengremel2 1 station de Sylviculture INRA-CRFChampenoux 54280 Seichamps and _ __ 2 Laboratoire de Physiologie Végétale et Forestidre Université de Nancy I BP 239 54506 Vandceuvre-les-Nancy France Introduction Young oak trees are very sensitive to weed competition especially brambles Rubus fruticosus L. . Bramble control is essential during the first years of establishment of oak regenerations. Glyphosate V-phosphonomethylglycine enables good control when applied in winter to green brambles Frochot and Wehrlen 1983 . However the tolerance of oak seedlings to the glyphosate treatments during the vegetative rest period was not clearly established. Previous studies demonstrated that glyphosate applied during the dormant period did not affect poplar growth Netzer and Hauser 1983 . Unfortunately this herbicide sometimes causes injuries to oak seedlings. Young oaks were shown to be as equally affected by glyphosate applied at the beginning as at the end of the rest period Frochot et al. 1981 . In this study we analyzed the effects of the period of herbicide application on phenological and physiological characteristics of oak seedlings. Materials and Methods 1 yr old oak seedlings Quercus petraea M. Liebl. were grown on fertilized peat in individual containers. Each treatment and control consisted of 24 seedlings. Experiments were carried out in a climate chamber simulating autumn and winter conditions during 8 periods of 14 d each. These periods were characterized by ranges of medium 1 5 8 high 2 4 6 and low 3 7 temperatures Fig. 1 The seedlings were subjected to an accidental period of low temperature indicated by an asterisk. The day-night regime was established as follows 8 h d at a temperature equal to the maximum average temperature
